Due to considerations such as ease of manufacturing or need for maintenance, components of a power plant assembly may be broken into sub-components that are joined to one another in a removable manner. A so-called parting line is formed where the sub-components come close to or contact one another and are separable from one another and may include a seal disposed between the components. When there is a differential pressure related to the sub-component, be it a differential pressure from interior to exterior, exterior to interior, or within the sub-component, there may be a tendency for the differential pressure to result in a flow across the parting line if the parting line is not adequately sealed.
Providing a seal across the parting line may be challenging if the sub-components encounter temperature changes or temperature gradients in service. For example, if the sub-components have a service temperature of several hundred, or even thousand, degrees Fahrenheit, the sub-components could undergo considerable thermal expansion as the sub-components reach operating temperature. This could cause dimensional changes along the parting line and such dimensional changes could change the characteristics of any seal along the parting line as the sub-components transition to the operating temperature. Even once the sub-components reach a steady state or semi-steady state operating temperature, a temperature gradient along the parting line could cause a seal to have different sealing characteristics along the temperature gradient. Even small dimensional variances along a parting line could result in considerable changes to sealing performance such that the seal becomes non-deterministic due to dimensional variances of the seal which can make prediction of where components contact one another, and/or where the components contact a seal, difficult.
Varying sealing characteristics may be of particular concern in turbines where efficiency is of particular importance. For example, even though leaks could be accounted for or even desirable, being able to model or predict the leaks is useful to control or measure the performance of the turbine. A particular component that may include such a parting line and/or seal is a diffuser in a turbine.